Acetate Acetylacetonate Ampy Ruthenium(II) Complexes as Efficient Catalysts for Ketone Transfer Hydrogenation. Issue 13 (19th May 2020) - Hey, Daniela A.
Abstract: The mixed acetate acetylacetonate (acac) ruthenium(II) phosphine complexes Ru(OAc)(acac)P2 [P2 =(PPh3 )2, Ph2 P(CH2 )4 PPh2 (dppb)] were prepared by protonation of Ru(OAc)2 (PPh3 )2 with acetylacetone in dichloromethane. Reaction of the dppb derivative with 2‐(aminomethyl)pyridine (ampy) affords the complex Ru(OAc)(acac)(ampy)(dppb), which converts to [Ru(acac)(ampy)(dppb)](OAc) in toluene at 90 °C. In the former derivative the ampy ligand is monodentate and coordinates through the NH2 ‐moiety. The isolated acac complexes are active catalysts for the transfer hydrogenation of ketones with loadings as low as 0.01 mol%, the ampy having a strong accelerating effect. Several aromatic and aliphatic ketone substrates are converted to their corresponding alcohols, and different electronic influences through substituents on acetophenone are tolerated. Abstract : Exploiting ligand properties : The ruthenium(II) complex Ru(OAc)(acac)(ampy)(dppb) with acetate, acetylacetonate, 2‐(aminomethyl)pyridine and diphosphine ligands is highly active in the transfer hydrogenation of ketones (TOFs up to 125, 000 h −1 ). Various substrates can be converted to their respective alcohols in quantitative yield and catalyst loadings as low as 0.01 mol %.